The present invention relates to the processing of cellular radio data, implemented by computer means of a SIM card, in particular in order to monitor the current location of a terminal that is housing the SIM card, for example for security purposes.
The terminal may, for example, be a device communicating with a server via a cellular radio network, such as a payment terminal in a store or restaurant. For security reasons, it is undesirable to enable a malicious user to misappropriate the terminal in order to steal data or for other purposes.
To this end, a remote server (for example a verification server) monitors the location of the terminal based on radiofrequency identifiers of the cells where the terminal is located. The SIM card of the terminal usually manages the transmission of cell change notifications to the server.
Thus, the SIM card of a terminal that is mobile usually receives from the network a current cell identifier (for example at regular times or when establishing communication), and transmits these cell identifiers to a server which uses these data to verify that the terminal has not moved beyond a certain distance from a predetermined position.
However, the receiving and processing by the server of all these notifications, each time a cell identifier is received, generates a large workload for the server.
To limit this problem, it could be provided that the SIM card:                compares the current cell identifier with an identifier previously stored in memory (typically the cell identifier indicated by the network at the previous moment, or during the last communication),        and then generates a notification for the remote server only if there is a difference between the current identifier and the cell identifier previously stored in memory.        
However, here again, in some situations, for example where the payment terminal is in a large restaurant or a department store covered by several cells at once, the mobile payment terminal can generate a large number of notifications from the SIM to the server, with each change of cell.
Such notifications would then reduce the SIM card processing speed, and the payment terminal would experience unnecessary delays. The server itself must still process all these notifications it receives even though these terminal locations are not unusual and are very close to the presumed original location.